SLOW DOWN light when cold — 2002 360 — Cat ECU’s ?

Seems odd that they are wanting to change both thermocouples and both thermocouple ECUs. It also sounds like they are wanting to use OEM ECUs.

Did they scan for faults? I doubt both ECUs would fail at the same time. Do you have a basic scanner?

Technistrada may have a cheaper solution on the ECUs and it's DIY.

https://technistrada.com/catalytic-temperature-control-station---355-360-456-550-575

 

This might be voltage related - if so, it can be fixed by charging or replacing the battery.

I personally would not spend 5k for replacing approximately 1k of parts, without having a clear diagnosis first.

 

Spend the $1K and change them yourself. Although, I would clear the error code and confirm if they come back, and on which side.

 

If you have a half hour, a 3 digit IQ, a Dollar General socket set, an internet connection, a 15 pack of Keystone, and working hands, you can do it yourself for literally 15% of what the dealer tried to scr...I mean quoted you for.

 

I replaced both computers and both 02 sensors due to that issue...Did myself...I actually bought a set of eliminators for the computer 2 but have not installed them yet. It happened 2 years later and I just replaced the 02 sensors...IT HAPPENS AGAIN IM GETTING A TUNE TO DELETE THE ISSUE lol